TIME-RESOLVED EMISSION-SPECTRA OF PLASMA PRODUCED BY EXCIMER-LASER ABLATION OF BI-SR-CA-CU-O AND Y-BA-CU-O SUPERCONDUCTORS IN THE AIR

Time-resolved emission spectroscopy was employed to detect excited species formed by the laser ablation of Bi-Sr-Ca-Cu-O and Y-Ba-Cu-O targets at atmospheric pressure. The emission spectra at times of up to 100 ns are characterized by the broadband emission of high-density plasma; for longer times, sharp atomic and ionic lines were found (Bi, Sr+, Sr, Ca+, Ca, and Cu for the ablation of Bi-Sr-Ca-Cu-O and Y, Y+, Ba+, and Cu for the ablation of Y-Ba-Cu-O). At times greater than 30 mus (Bi-Sr-Ca-Cu-O) or 2 mus (Y-Ba-Cu-O) primarily excited metal oxides occurred in the plasma. Experiments in oxygen, nitrogen. argon, and helium atmosphere indicate that part of the excited metal oxides are formed by reaction of the excited species with molecular or atomic oxygen.